1. Field of the Invention
The present invention relates to data correction apparatus and method for correcting data when page description data representing pages containing images and texts is converted into raster data for printing, as well as a program for causing a computer to carry out the data correction method.
2. Description of the Related Art
Conventionally, in the field of printing, DTP (DeskTop Publishing), which uses a computer to carry out editing operations, has widely been applied. DTP realizes the idea of “WYSIWYG” (What You See Is What You Get), which allows an operator to edit texts and images with viewing them displayed on a screen to check the appearance of prints before printing the images and texts on a printer or the like.
A software used in DTP by the operator for editing texts and images is generally called a DTP software. The DTP software generates data in a format referred to as page description data, which represents the appearance of respective pages, based on the texts and images edited by the operator. Since the page description data cannot directly be output by an output device such as a printer, the page description data is converted into raster data, which can be outputted by the output device, by a RIP (Raster Image Processor), and then the output device outputs an output image based on the raster data.
Along with spread of digital cameras, photographed images taken with digital cameras are widely used as images for printing. Photographed images may have problems such that a photographed image taken against the sun is paler. In such cases, a retouching software for modifying the images is used to correct colors of each photographed image. Manually correcting colors of images using a mouse or the like requires a high level of skill. However, in recent years, a retouching software having an automatic setup function has been known, which analyzes characteristics of colors of an image such as tones of colors, and automatically applies color correction depending on the characteristics to the image. The operator can use the automatic setup function of the retouching software to automatically calculate setup conditions and apply color correction to images based on the setup conditions, and then, using a DTP software, the operator paste the images, which have been subjected to the color correction and have colors pleasing to the eye, on a page represented by page description data.
However, if a large number of photographed images are used as images for printing, it is extremely troublesome and time-consuming to start up the retouching software, apply color correction to each photographed image, and paste the images on pages, even with the above-described automatic setup function.
Such troublesomeness is particularly problematic when a printer for printing called an on-demand printer is connected to the RIP to produce prints. Unlike a printing press, the on-demand printer does not require plate making, and thus can significantly reduce printing costs and processing time for outputting images. Therefore, in recent years, the on-demand printers are widely used for creating business documents, and the like. Since prints produced with the on-demand printers are typically not expected to have image quality as strict as prints produced through large-scale operations with a printing press, users of the on-demand printers have strong demands for a technique that allows the users to easily carry out a series of editing operations, including the above-described color correction, without taking much time. In particular, there are increasing demands for a technique that allows the users to paste photographed images taken with digital cameras on business documents and alleviates the above-described troublesome operations.
A technique has been proposed, in which images in a page represented by page description data are recognized, and correction is applied to each of the recognized images using the automatic setup function (see U.S. Patent Application Publication No. 20040234156). According to this technique, time and effort for producing output images including the images subjected to image correction can be reduced.
In a case where multiple natural images taken with a digital camera are contained in a page, the natural images may be similar to each other such that the same person is contained in the natural images or the natural images have similar colors to each other. According to the technique described in the above U.S. Patent Application Publication No. 20040234156, such similar natural image being similar to each other are separately subjected to image correction by the automatic setup function. As a result, although the images are similar to each other, they may have different image qualities such as lightness and/or colors after the image correction, and this may introduce inconsistency to the page containing these images.